ACATS B tests

[dewar@gnat.com]

<<OK, I give up.  Why is that?  Is it because the error was supposed to be
on the *previous* line?
>>

Nope. Not necessarily, for example there are cases where the ACVC test
expects the error message on the definition instead of the reference
or vice versa, and there are cases where the ACVC expects a cascaded
error where we deliberately suppress it, and there are cases where
GNAT generates cascaded errors where none are expected etc etc.